Extruded encapsulated fillers to provide crush protection

ABSTRACT

In various embodiments, a tubular comprises a tubular outer sheath defining an inner void; one or more core elements or assemblies disposed within the inner void; and a substantially solid filler in various embodiments disposed within and substantially filling the inner void, where the filler is adapted to give the tubular hoop strength in a crush situation and comprises a polymer with a density of at least 1.0. In some embodiments, these core assemblies comprise an extruded polymer layer typically extruded about core elements in a single pass, fitting about them without a sharp edge and defining an outer shape. The resulting tubular can comprise multiple regions which, though substantially filled, are filled with differing fillers densities.

RELATION TO PRIOR APPLICATIONS

This application claims the benefit of Provisional Application61/861,796 for “System and Method for Adjusting the WDR Ration ofUmbilicals By Varying Density of Fillers,” filed Aug. 2, 2013.

FIELD OF THE INVENTION

The invention relates to strengthening and protecting componentsdisposed within a flexible tubular. More specifically, this inventionrelates to use of an extruded polymer shape disposed about an internalcore element disposed within the flexible tubular, e.g. an umbilical, toprovide crush stiffness to the internal core element, for example use ofan extruded polymer shape disposed about an armor wire used for tensilestrengthening when disposed about the internal core element.

BACKGROUND OF THE INVENTION

Polymeric fillers are a necessary part of the geometry of most flexibletubulars, such as umbilicals, and are used as packing, often as round,separate components disposed within the tubular. However, because mostfiller plastics used in the construction of umbilicals have a specificgravity of less than or equal to 1.0, it becomes costly and/or difficultto design umbilicals which meet specific weight requirements orweight-to-diameter ratios. Desired weight considerations can includesuitability for dynamic and/or seabed stability, and will often resultin having to add additional armor passes, which in turn increases theouter diameter (OD) of the umbilical. This adds additional cost and,more importantly, adds additional weight which in turn increases thetensile loading of the umbilical and often puts more strain on theinternal core elements, resulting in larger crush forces duringinstallation and recovery.

Current umbilical art also requires maintaining a high density in anumbilical, which may make it more stable while hanging from the platformor on the sea floor. Because many plastics comprise densities close tothe density of water and because there is typically a lot of open spacein an umbilical, manufactures are often forced to use a significantamount of armor, e.g. steel or other metal, on the umbilical to increaseits density. However, as the amount of armor needed for density isincreased, the total amount of armor also rises to be able to hold upthe weight of the umbilical, resulting in a larger umbilical larger.When the umbilical is installed, this extra weight may present asignificant load and the deploying mechanism, e.g. a vessel, has toapply a large crush tension (normal force) to keep the umbilical fromslipping through the deploying device. This crush load may be high anddamage interior core elements such as hoses, reducing the lifespan ofthe umbilical and its core components.

Accordingly, current art typically uses polymeric fillers as packingaround internal components. These internal components may be strandedtogether in a helix and a layer of polymeric fillers such aspolyethylene extruded over them; the components may then be stranded,often in an S-Z pattern over an internal core. An extruded sheath isthen disposed over the bundled components with armor such as steel rodsstranded over the outside, e.g. helically. Finally, another sheath isextruded over the armor. This design has shortcomings. For example, ahigh density in the umbilical is required, making it more stable whilehanging from the platform or on the sea floor because the plastic usedis very close to the density of water and there is a lot of open spacein the umbilical. This, in turn, requires use of a lot of armor on theumbilical to increase its density but as the amount of armor increasesfor density an even greater amount of armor is required to be able tohold up the weight of the umbilical, making the umbilical larger.Another shortcoming is that an umbilical being installed is oftengripped by a tensioner while up to 2500 m of umbilical are hanging offthe end of the vessel. This is a significant load for the cable and thevessel has to apply a large crush tension (normal force) to keep theumbilical from slipping through the tensioner. This crush load candamage internal umbilical components such as hoses and reduces thelifespan of those components.

BRIEF DESCRIPTION OF THE FIGURES

The figures supplied herein disclose various embodiments of the claimedinvention.

FIG. 1 is a cross sectional view in partial perspective of an embodimentof a flexible tubular comprising an outer sheath, inner sheath,functional components, and substantially solid filler;

FIG. 2 is a cross sectional view in partial perspective of an embodimentof a flexible tubular comprising an outer sheath, inner sheath,functional components, armor, and filler;

FIG. 3 is a cross sectional view in partial perspective of an embodimentof a flexible tubular comprising an outer sheath, inner sheath,functional components, armor, and shaped fillers;

FIG. 4 is a cross sectional view in partial perspective of an exemplarycomponent, and filler;

FIG. 5 is a cross sectional view in partial perspective of an embodimentof a flexible tubular comprising an outer sheath, inner sheath,functional components, armor, and shaped fillers;

FIG. 6 is a cross sectional view in partial perspective of a portion ofthe embodiment of FIG. 5; and

FIG. 7 is a representational view of an embodiment of a flexible tubularcomprising a region or greater filler density and a region of lesserfiller density.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

In general, as will be understood by those of ordinary skill in theumbilical arts, “sheaths” are also sometimes referred to as outerextrusions or jackets and may comprise polyethylene, polyurethane orother suitable thermoplastic. A “core element” such as core element 32in FIG. 1 may comprise a functional element such as a hose, electricalcable, fiber optic bundle, steel tube, or the like, or a combinationthereof. Many such functional elements may be present and may further beconfigured as desired, e.g. in a helix strand or an S-Z pattern.

Referring now to FIG. 1, tubular 1, which can be a flexible tubular suchas an umbilical suitable for subsea use, comprises tubular outer sheath20, defining inner void 24; one or more core elements 32 disposed withininner void 24; and substantially solid filler 31 disposed within andsubstantially filling inner void 24.

Filler 31 typically comprises a polymer having a density of at least1.0. The polymer typically comprises a high density polyethylene and maybe selected or otherwise configured to provide impact and fatigueprotection for one or more core elements 32, e.g. hose 32 a (FIG. 2),electrical conductor 32 b (FIG. 2), or fiber optic conductor 32 c (FIG.2), as well as configured to give tubular 1 a predeterminedcharacteristic such as predetermined hoop strength in a crush situation.

Referring additionally to FIG. 2, in certain configurations tubularinner sheath 23 may be present. As in other embodiments, tubular 1 istypically flexible and, by way of example and not limitation, be anumbilical such as an umbilical suitable for use subsea. Tubular innersheath 23 is disposed within inner void 24 and, accordingly, has acircumference small than the inner circumference of tubular outer sheath20. Tubular inner sheath 23 defines first space 24 a between an outercircumference of tubular inner sheath 23 and the inner circumference oftubular outer sheath 20 and second space 24 b within inner void 24inside tubular inner sheath 23. In these embodiments, filler 31 isdisposed within and substantially fills second space 24 b. Armor 22,which may comprise steel or other wire such as a mesh or othercollection of wire, may also be present and disposed within an armorvoid defined by first space 24 a.

Referring now to FIG. 3, in a further embodiment tubular 1 comprisestubular outer sheath 20 defining inner void 24; a plurality of coreassemblies 30 disposed within inner void 24; and a plurality of fillers310 disposed about core assemblies 30 within and substantially fillinginner void 24.

Filler 310 typically comprises a polymer having a density of at least1.0 such as, by way of example and not limitation, a high densitypolyethylene, and may be selected or otherwise configured to provideimpact and fatigue protection for one or more core elements 32 (FIG. 4).Filler 310 may be a shaped component that is round, obround, or anyother shape appropriate to substantially fill the interstices created bycore assemblies 30.

Referring additionally to FIG. 4, core assemblies 30 comprise one ormore core elements 32, which, in turn, may comprise a fluid hose, anelectrical conductor, a fiber optic conductor, or the like, or acombination thereof. As these are conventional items, they are generallyshown as core element 32.

Core assemblies 30 also typically comprise one or more shaped extrudedpolymers layer 33 configured to help give tubular 1 (FIG. 3) hoopstrength in a crush situation. Extruded polymer layer 33 is typicallyshaped with a substantially rounded outer circumference and extrudedaround core element 32 in a separate process which typically does notbind polymer layer 33 to core element 32. The selected shape may beadapted and configured to help provide crush stiffness to tubular 1 andmay be a rounded shape, an obround shape, an S-Z stranded shape, ahelically stranded shape, or the like, or a combination thereof. Ifrounded, the rounded shape may provide core assemblies 30 comprisingrounded extruded polymer layer 33 an ability to twist within thestranding process. Further still, extruded polymer layer 33 may beconfigured to provide impact and fatigue protection for soft componentswithin inner void 24.

Referring now to FIG. 5, in a further embodiment, tubular 1 comprisestubular outer sheath 220 defining inner void 24 and a plurality of coreassemblies 320 disposed within inner void 24.

Tubular outer sheath 220 may further comprise outer surface 221 definingan outer circumference, inner sheath 223 comprising an inner surfacedefining an inner circumference in which outer sheath void 225 existsbetween outer surface 221 and inner sheath 223, and armor 222 disposedwithin outer sheath void 225.

Referring additionally to FIG. 6, in certain configurations tubular 1further comprises substantially tubular inner jacket 60 disposed withininner void 24. In these configurations, each core assembly 320 isdisposed within inner void 24 intermediate inner sheath 223 and outersurface 61 of inner jacket 60 and extruded polymer layer 333 (FIG. 6) isshaped to substantially fill inner void 24 between outer sheath 220 andouter surface 61 of inner jacket 60.

Core assemblies 320 comprise one or more core elements 32 and polymerlayer 333 which is extruded about core elements 32 in a separate, singlepass process that does not bond polymer layer 333 to the core elements32 of their respective core assembly 30. Polymer layer 333 defines afiller that typically comprises a polymer having a density of at least1.0, typically a high density polyethylene, and may be selected orotherwise configured to provide impact and fatigue protection for one ormore core elements 32. As with the other embodiments, core elements 32may comprise a fluid hose, an electrical conductor, a fiber opticconductor, or the like, or a combination thereof.

In these embodiments, extruded polymer layer 333 is shaped tosubstantially and precisely fit about core elements 32 without leavingan exposed sharp edge. Typically, each polymer layer 333 is furthershaped to interface with the remaining core assemblies 330 (FIG. 5) tosubstantially fill inner void 24 when core assemblies 330 are disposedwith inner void 24. The shape may comprise an outer arcuate shapeadapted to allow core assembly 330 to fit inside inner void 24 which isadapted to be able to twist within a stranding process. The shape mayalso comprise an outer sector or locking shape adapted to providelateral stability for tubular 1, an S-Z stranded shape, a helicallystranded shape, or the like, or a combination thereof. The shape mayalso be configured to provide impact and fatigue protection for softcomponents, hoop strength in a crush situation, crush stiffness, and thelike, or a combination thereof.

Referring now to FIG. 7, in a further embodiment, tubular 1 comprisesouter sheath 20 defining interior conduit 13 which further comprisesfirst defined region 11 and second defined region 12. This configurationcan comprise any of the embodiments described herein above. As describedabove, one or more functional components such as core elements 32 (e.g.,FIG. 1) are disposed within interior conduit 13, either by themselves oras part of core assemblies (e.g. core assembly 30 (FIG. 3) or coreassembly 320 (FIG. 6)).

First filler 31 a, comprising a first density of at least 1.0, isdisposed within and substantially fills first region 11 and secondfiller 31 b, comprising a second density with a density of at least 1.0that is different than the first density, is disposed within andsubstantially fills second region 12. First filler 31 a and secondfiller 31 b are chosen or otherwise adapted to comprise a predeterminedcharacteristic such as a characteristic sufficient to improve crushprotection provided to the functional components core elements 32 (e.g.,FIG. 1), core assembly 30 (FIG. 3), and/or core assembly 320 (FIG. 6)).First filler 31 a and/or second filler 31 b may comprise a two piecefiller, a conventional design, a split and folded over shape, or thelike, or a combination thereof.

As with other embodiments, inner shell 60 (FIG. 5) may be present anddisposed intermediate outer sheath 20 and functional components 30 (FIG.1). Inner shell 60 may comprise interior surface 62 (FIG. 5) defininginterior void 50 (FIG. 5) and outer surface 61 (FIG. 5), and functionalcomponents 30 are disposed within interior void 50. In thisconfiguration, interior conduit 13 is defined by the area between aninterior of outer sheath 20 and outer surface 62 of inner shell 60.

As with other embodiments, armor such as armor 225 (FIG. 5) may bedisposed within and/or about conduit 13.

In all of these embodiments, tubular 1 is typically flexible and, by wayof example and not limitation, be an umbilical such as an umbilicalsuitable for use subsea. In all of these embodiments, core elements 32(e.g. FIG. 6) may comprise a fluid hose, an electrical conductor, afiber optic conductor, or the like, or a combination thereof. All ofthese embodiments may comprise substantially tubular inner jacket 60(FIG. 5) disposed within inner void 24, where inner void 24 is definedinteriorly by outer surface 61 of inner jacket 60 and the variousfillers described herein substantially fill inner void 24 between therespective outer sheath and outer surface 61 of inner jacket 60.

In the operation of preferred embodiments, referring generally to FIG.1, flexible tubular 1, which may be an umbilical, may be constructed bydetermining a strength for filler 31 to achieve a predeterminedobjective for flexible tubular 1. Typically, flexible tubular 1, e.g. anumbilical, is as described above and comprises outer sheath 20 whichdefines interior void 24. A specific filler density is determined whichwill achieve the predetermined objective, the density being at least1.0. Once these determinations occur, filler 31 is obtained where filler31 comprises the required specific filler density, e.g. a plastic orother polymer material comprising a density of at least 1.0. One or morecore elements 32, core assemblies 30 (FIG. 3), and/or core assemblies320 (FIG. 6) may be disposed within interior void 24 and may compriseone or more conventional, functional elements such as hoses or cables.Typically, these core elements 32, core assemblies 30, and/or coreassemblies 320 are disposed in interior void 24 which is thensubstantially filled with filler 31 such that filler 31 typicallysurrounds these core elements 32, core assemblies 30, and/or coreassemblies 320 in interior void 24.

In certain multi-region embodiments such as illustrated in FIG. 7, aplurality of fillers 31 are desired. For example, first filler 31 a maycomprise a desired buoyancy characteristic whereas second filler 31 bmay comprise a stability characteristic. In this manner, first region 11may be heavier than second region 12, allowing first region 11 to remainmore stabile when deployed, e.g. subsea, with respect to second region12 which can be more buoyant. In these embodiments, first filler 31 acomprises a first specific filler density to achieve a firstcharacteristic for first region 11 and second filler 31 b comprises asecond specific filler density to achieve a second characteristic forsecond region 12. One of the first specific filler density and thesecond filler density may be greater than the second the other density.First region 11 is substantially filed with the first filler and secondregion 12 is substantially filed with the second filler.

If armor is used, e.g. armor 22 (FIG. 2, FIG. 3) or armor 225 (FIG. 5),such armor may comprise a wire, e.g. a metal wire such as steel, toprovide tensile strength. For example, armor 22 or 225 may be wound atlow lay angles from 8 to 12 degrees. The extruded polymer shape may thenbe used to provide crush stiffness to the functional components.

The foregoing disclosure and description of the inventions areillustrative and explanatory. Various changes in the size, shape, andmaterials, as well as in the details of the illustrative constructionand/or illustrative methods may be made without departing from thespirit of the invention.

What is claimed is:
 1. A tubular, comprising: a. a tubular outer sheathdefining an inner void; b. a core element disposed within the innervoid; c. a substantially solid filler comprising a polymer, the polymercomprising a density of at least 1.0 and a predetermined hoop strengthin a crush situation, the filler disposed within and substantiallycompletely filling the inner void and in contact with and substantiallycompletely surrounding the core element; and d. a tubular inner sheathhaving a circumference smaller than the tubular outer sheath, thetubular inner sheath disposed within the inner void and defining: i. afirst space between an outer portion of the tubular inner sheath and aninner portion of the tubular outer sheath; and ii. a second space withinthe inner void inside the tubular inner sheath, the filler disposedwithin and substantially filling the second space.
 2. The tubular ofclaim 1, further comprising ii. an armor wire disposed within the firstspace.
 3. The tubular of claim 1, wherein the polymer comprises highdensity polyethylene.
 4. The tubular of claim 1, wherein the polymer isconfigured to provide impact and fatigue protection for the coreelement.
 5. The tubular of claim 1, wherein: a. the tubular comprises anumbilical cable adapted for use subsea; and b. the core elementcomprises a fluid hose.
 6. The tubular of claim 1, wherein the coreelement comprises at least one of a fluid hose, an electrical conductor,and a fiber optic conductor.
 7. The tubular of claim 1, wherein thetubular comprises a flexible tubular.
 8. A method of manufacturing atubular, comprising: a. placing a tubular inner sheath within aprotective outer sheath about a core element, an interior surface of theouter sheath defining an inner void with respect to the tubular innersheath, the tubular inner sheath defining: i. a first space between anouter portion of the tubular inner sheath and an inner portion theprotective outer sheath; and ii. a second space within an inner voidinside the tubular inner sheath; b. disposing the core element and thefiller within the second space; and c. using a substantially solidpolymer filler, the substantially solid polymer filler comprising animpact and fatigue protection material comprising a polymer with adensity of at least 1.0 that provides tubular hoop strength in a crushsituation, the impact and fatigue protection material, to substantiallycompletely fill the second space and surround the core element.
 9. Themethod of manufacturing a tubular of claim 8, further comprising: a.disposing an inner sheath within the outer sheath; and b. disposing anarmor in an armor void defined by an inner surface of the outer sheathand an outer surface of the inner sheath, the polymer fillersubstantially filling a void defined by an interior surface of the innersheath.
 10. The method of manufacturing a tubular of claim 9, furthercomprising using an armor comprising a metal adapted to provide tensilestrength with a winding at low lay angles from around 8 degrees toaround 20 degrees.